Dataset for "An Integrated Shipboard Workflow for Rapid Radiocesium Determination in Seawater: Validation at Open-Ocean Background Levels"

This dataset supports the manuscript entitled “An Integrated Shipboard Workflow for Rapid Radiocesium Determination in Seawater: Validation at Open-Ocean Background Levels.” The dataset contains the numerical data used for Figures 4–7 of the manuscript, including: (1) paired measurements of Cs-137 activity obtained using the shipboard method and the conventional land-based ammonium phosphomolybdate (AMP) method; (2) surface Cs-137 activities at stations A1–A5 from 2023 to 2025; (3) vertical profiles of Cs-137 at station A1 in October 2023 and historical data from StW06 reported by Kaeriyama et al. (2016); and (4) hydrographic data, including depth, temperature, salinity, potential density anomaly, dissolved oxygen, latitude, and longitude, used for water-mass characterization. Cs-137 activities are reported primarily in mBq/kg. Where applicable, activities were decay-corrected to 1 January 2026 using a Cs-137 half-life of 30.17 years. Additional information on units, decay correction, and historical-data conversion is provided in the README worksheet.